Phase Diagram of LiCl-NaCl-AlCl3 Ternary System

Phase diagram of LiCl-NaCl-AlCl 3 ternary system has been determined by the use of direct visual observation and DTA methods. Composition ranges studied are 0–100mol% AlCl 3 for LiCl-AlCl 3 and NaCl-AlCl 3 binary systems, and 0 – 50mol% AlCl 3 for the ternary system. Chemical compounds LiAlCl 4 and NaAlCl 4 were found in the binary systems and their melting temperatures are 416K and 427K, respectively. The ternary system in the composition range less than 50mol% AlCl 3 shows two liquidus surfaces around LiCl and NaCl, and one boundary line between them. The ternary eutectic composition is considered to be near the eutectic composition of LiAlCl 4 -NaAlCl 4 binary system although it could not be found. It is considered that the ternary system is a reciprocal system of (Li + , Na + || Cl − , AlCl 4 − ) in the composition range less than 50mol% AlCl 3 . From the slopes of liquidus surfaces of the reciprocal melt, the standard free energy change of the following ion exchange reaction is estimated to be positive.